Choke control device for shotgun barrels



A118- 25, 1959 v. A. BRowNlNG 2,900,752

ciHoKE CONTROL DEVICE FOR sHoTGuN BARRELs Filed Feb. 3, 1958 2 Sheets-Sheet 1 V. A. BROWNING CHOKE CONTROL DEVICE FOR -SHOTGUN BARRELS Aug. 25, 1959 2 Sheets-Sheet 2 Filed Feb. 3. 1958 RG E mw m mN m Vw T No A. M L m M V.. Nm, ,who u Il @il R l. l I l l I l l l l l l 1 l l l I I I l I ||9||l||| flllnm W :L llf1|# IJ... V D w l `L M` l N NN Q w .wm N5 n wm um um S o. Nw m m United States Patent CHOKE CONTROL DEVICE FOR SHOTGUN BARRELS Val A. Browning, Ogden, Utah, assignor to Browning Industries, Inc., Ogden, Utah, a corporation of Utah Application February 3, 1958, Serial No. 712,931

6 Claims. (Cl. 42-79) This invention relates to firearms and more particularly to a novel and improved mechanism for adjustably changing the choke pattern of a shotgun.

A major object of the invention is to utilize the explosive -gases generated upon tiring a pellet charge 1n a manner to modify the choke pattern resulting from the choke characteristics of the bore as the choked pellets pass through the muzzle end of the barrel.

Another object is to provide a fully choked shotgun barrel with a readily accessible manually operable control to permit use of the gun in a conventional manner, or alternately to by-pass explosive gases from a rear to a forward bore portion for choke pattern modification, and -to do so with the addition of little or no weight to the barrel, and without detracting from the appearance thereof.

A further object is to provide a choke changing device adapted for installation on a shotgun having a recoilable barrel in a manner to permit manual adjustment to obtain a modified choke pattern of the first shot and re- Y construction, combination of elements and arrangement of parts which will be exemplified in the construction hereafter set forth and the scope of the application of which will be indicated in the appended claims.

In the drawings:

Fig. 1 shows in elevation a recoilable shotgun barrel incorporating the invention.

Figs. 2 and 3 show in vertical axial section the barrel of Fig. l, the rear portion being shown in Fig. 2 and the front section, broken therefrom, shown in Fig. 3.

Fig. 4 is a plan view of the same barrel, broken along the axis, and illustrating gas ports and control valve structure.

Fig. 5 is a sectional view of the muzzle end taken along line 5--5 of Fig. 4.

Fig. 6 is a sectional View of the main barrel portion taken along line 6-6 of Fig. 4.

Referring to Figs. l, 2, and 3 illustrating the same recoilable shotgun barrel, generically designated 10, a barrel extension portion 11 is slidably disposed in a receiver portion 12, extension 11 and rear portions of barrel 10 dening a breechblock chamber 13, leading into a cylindrical cartridge chamber 14.

Chamber 14 tapers at 16 to lead into a cylindrical main bore portion 15, shown broken in Figs. 2 and 3, and extending a substantial length of the barrel, to lead into a tapered choke cone portion 17 formed by a gradual reduction of the main bore diameter starting at 18 and ending at 19, Fig. 3, to lead, at 19, into a cylindrical muzzle bore 20. A forearm 22 and sight 23, as well as the above described barrel structure are of conventional design, the inventive principles taught herein being adapted for incorporation in conventional barrels by sim- ICC ple modication thereof. For example, a recoilable barrel of the type illustrated in U.S. Patent No. 2,626,475 issued to the same inventor may easily be modified to incorporate the invention.

Fig. 3 is a view taken momentarily after a fired cartridge has propelled shot pellets 24 and multipleV layers of cartridge wadding 25, through the main barrel portion to pass partially through the choke cone 17 and into muzzle bore 20. Wadding 25 is shown about to enter cone 17 behind pellets 24 which are choked into a tight pattern during passage through choke cone 17 to pass through muzzle bore 20 in that pattern unless otherwise modified in a manner comprising this invention. It may be assumed, for present purposes, that a full choke pattern results from .pellet passage through cone 17. Such a pattern, as well known in the art, is determined by measuring shot concentration within a measured area and at a measured distance from the muzzle of a gun after discharge.

Conditions of use dictate the desirability of modifying by manually operable means, or automatically during a sequence of shots, the shot pattern of such a gun, hence various pattern modifying devices have been developed for attachment to or incorporated in the structure of both automatic and non-automatic Shotguns. It is highly desirable to permit a user to utilize the advantages of a built-in full choke and rapidly to modify that pattern, either manually or automatically after tiring the first shot, while using the same barrel, and the present invention accomplishes that objective in the following manner:

As shown in Figs. 2 and 3, the rupper wall of barrel 10 is apertured somewhat forward of the cartridge chamber to provide a gas port 27 extending therethrough. A second gas port 28, in axial alignment with port 27, extends through barrel 10 near the muzzle end thereof. Ports 27 and 28 are interconnected externally of the barrel wall by an elongate gas passage 30, rectangular in cross section and formed by an elongate channel member 32, U- shaped in cross section and brazed or otherwise bonded, inverted as shown, to a planiform shoulder 33 extending along the top of fbarrel 10 and formed integrally therewith as best shown in Fig. 5. The top wall surface 34 of channel member 32 from which side walls 35 depend serves also as a sighting rib, hence side walls 35 are suitably contoured to compensate for the forward taper of the barrel as shown in Fig. l to align wall 34 with the bore axis.

The front end of channel member 32 is suitably closed at 36 to terminate gas passage 30 slightly forward of port 28, but the rear end isleft open, as best shown at 37, Figs. 2 and 4, for reception of a slide valve 38 comprising an elongate shank, rectangular in cross section, for snug slidable reception in channel 30, effectively to close that channel to lgas passage therethrough. Valve 38 also includes a T-shaped end portion 40 disposed transversely `of the shank to form Igrips for manual adjustment, preferably arced downwardly as shown in Fig. 6. The rear edge of grip 40 is adapted for contact with the front shoulder 39 of receiver 12 during automatic operation of valve 38 as later described. Valve 38, as shown in Fig. 4, is fully inserted within channel 30, its shank portion extending iforward of and closing port 27 to terminate at position 42 as shown.

With member 38 in the fully inserted position above described, barrel 10 will give a shot pattern dependent entirely on its built-in choke characteristics, since while port 28 is still open, it merely leads into a short section of passage 30, the remainder of the passage being blocked by valve 38, which Iwill fill with gas before the shot pellets reach the muzzle section, hence can exert no inuence on the pattern of shot passing through muzzle bore 20.

To eect shot pattern modification, the user simply draws back slide valve 38, by means of grips 40, to a fully retracted position, shown in Fig. 2 with grips 40 abutting shoulder 39 of receiver 11, to withdraw the opposite end of slide 38 from the position shown at 42, Fig. 4, to that shown at 45, Fig. 2, thereby opening port 27 and connect it, through passage 30, for gas communication with port 28.

Assuming port 27 open, by retraction of valve 38 to the position shown in Fig. 2, as the high pressure gases generated by cartridge discharge propel pellets 24 and wadding 25 past port 27 part of the gases, under very high pressure, pass therethrough and through channel 30 to enter muzzle bore 20 through port 28. Since the g gases iiowing through the length of channel 30, being much lighter than the charge of shot pellets, move with greater velocity along the channel and around the charge of shot pellets and wadding as the latter are passed through `the bore. The gases, under considerable residual pressure, re-enter the bore through port 28 in front of the shot charge `to establish a radially directed gas jet through which the pellets pass upon their arrival, momentarily thereafter, at the muzzle bore end of the barrel as shown in Fig. 3. The gases thus re-introduced to the bore near the muzzle end have a disturbing effect on the pattern established by pellet travel through the built-in choke portion, with the pattern symmetrically opened up or dispersed to result in a uniformly modified pattern, meaning something less than a full choke pattern established by built-in choke bore 17. The extent to which the pattern is modified may be controlled by proper selection of the bore diameter of ports 27 and 28.

Satisfactory pattern modification has been obtained in a fully choked 12 gage barrel with port diameters in the order of 1A. Gas pressures in the order of 8000 pounds per square inch are normally established in such a bar-rel at `the instant the pellets and wadding pass port 27 with that pressure decaying to about 100 pounds per square inch at the instant the gas spurts through port 28 into muzzle bore 20.

The gases thus re-introduced through port 28 do not distort the pellet pattern but effectively open it up without destroying the symmetry thereof.

As shown in Fig. 2, channel 30 is linear throughout the length thereof but the receiver portion of barrel 10 diverges conically toward the rear, starting from about rthe rear end of channel bar 32, hence when slide valve 38 is drawn rearwardly toward abutment with shoulder 29 of receiver 12 that portion of the shank of valve 38 adjacent end portion 40 is slightly arced upwardly to provide clamping pressure between the end 40 and'the barrel suliicient to hold the valve in any desired position of adjustment between the end of channel bar 32 and the receiver shoulder 39. To effect shot modification, it is merely necessary to draw grips 40 rearwardly a sufficient amount to bring the end of the valve shank clear of port 27. In any position of adjustment of grips 40, and regardless of whether the grips are brought into abutment with shoulder 39, recoil of barrel 10 in receiver 12 will move ythe valve 38 forward sufficiently to position the inner end 45 thereof forward of port 27 to close that port. I-t may be assumed however, for the purpose of the above description of the barrel shown in the drawings, that barrel 10 recoils in receiver 12 substantially the distance between the rear edge of grips 40 and receiver shoulder 39.

I claim:

l. In a shotgun barrel of the type defining a cartridge chamber, a main bore, a choke bore and a muzzle bore,

4 1 a pair of gas ports extending through the barrel, one ahead of the cartridge chamber but rearwardly of the choke bore and the other forward of the choke bore and near the muzzle end of the barrel, a gas conduit connecting said ports externally of the barrel, and valve means for closing said outlet port to prevent gas ow to said conduit.

2. A shotgun barrel having a bore provided with a cylindrical main section extending substantially throughout the major portion of `the barrel, and a straight sighting rib lalong the top of the barrel provided with a longitudinal passageway communicating at its rear end with said bore forwardly of the firing chamber and communicating at its forward end with said bore at the muzzle end of the barrel.

3. A shotgun barrel having a firing chamber and a muzzle bore, a sighting rib extending along the top thereof and channeled to define a longitudinal gas conduit, said conduit leading at its rear end into said barrel through a port forwardly of the firing chamber and leading at its forward end into said muzzle bore, a valve having a shank portion slidably disposed in said conduit with the inner end thereof projectable forwardly of said rear port to block gas flow between said port and conduit.

4. In a shotgun, a receiver having a shoulder at its forward end, a recoilable barrel supported by the receiver and having a bore with a tiring chamber at its rear end and a passageway leading from said bore in advance of the firing chamber into said bore adjacent the muzzle end of said barrel, and a longitudinally slidable valve having an elongate element for opening and closing said passageway, said valve being engageable with said shoulder upon recoil of the barrel for moving the valve in closed position.

5. In a shotgun, a barrel having a bore, a cartridge chamber at the rear end thereof, and a pair of axially spaced aligned gas ports extending through the barrel wall, one forward of the cartridge chamber and the other near the muzzle end, a sighting rib on the top wall of the barrel and having a channel connecting said ports to provide gas communication therebetween, the channel being closed at its forward end and open at its rear end, and an elongate slide element positioned in the rear end of the channel for selectively closing or opening said first mentioned port for control of gas communication between said ports.

6. A shotgun barrel having a cartridge chamber, a main bore, a choke bore and a muzzle bore, a gas outlet port extending through the barrel ahead of the cartridge chamber, a gas inlet port extending through the barrel at the muzzle bore, and a closed conduit connecting said ports externally of the barrel to allow explosive gases to be bypassed from the cartridge chamber to the muzzle bore to open up the shot pattern of the pellets travelling through the muzzle bore.

References Cited in the file of this patent UNITED STATES PATENTS 819,995 Heitkamp May 8, 1906 1,469,918 Maine Oct. 9, 1923 FOREIGN PATENTS 455,791 France June 2, 1913 300,428 Italy Sept. 8, 1932 

